The presently disclosed embodiments relate to applying release agents to fusers to facilitate heat and pressure fixing of marking particles in imaging devices such as, for example, xerographic printing devices; and, more particularly, to turbidity sensors that can be used to monitor the release agent.
The basic principles of electrostatographic printing with dry marking material (hereinafter generally referred to as “xerography,” “xerographic printing,” and/or the like) are well known: a light image of an original to be copied is typically recorded in the form of a latent electrostatic image upon a photosensitive member with subsequent rendering of the latent image visible by the application of electroscopic marking particles, commonly referred to as toner. The visual toner image can be either fixed directly upon the photosensitive member or transferred from the member to another support, such as a sheet of plain paper, with subsequent affixing of the image thereto in one of various ways, for example, as by heat and pressure. To affix or fuse electroscopic toner material onto a support member by heat and pressure, the temperature of the toner material is typically elevated to a point at which its constituents coalesce and become tacky while and pressure is simultaneously applied, thus causing the toner to flow to some extent into the fibers or pores of the support member or otherwise upon the surface thereof. Thereafter, as the toner material cools, solidification of the toner material occurs and the toner material becomes bonded firmly to the support member.
One arrangement for minimizing some of the problems associated with heat and pressure fusing, particularly offsetting, has been to provide the fuser roll with an outer surface or covering of polytetrafluoroethylene, widely distributed under the trademark TEFLON®, to which a release agent such as silicone oil is applied, the thickness of the TEFLON®. material being on the order of several mils and the thickness of the oil being less than 1 micron. To ensure and maintain good release properties of the fuser roll, it has become customary to apply release agents to the fuser members to ensure that the toner is completely released from the fuser roll during the fusing operation. Typically, these materials are applied as thin films of, for example, silicone oils to prevent toner offset. Release agent management (“RAM”) systems have been used as parts of roll fuser apparatuses for some time.
Xerographic printing devices are capable of printing with a normal color toner or with a special clear toner. Each toner requires a specific release agent or fuser fluid to be loaded. A technician has to know that they must manually load either a first type of fuser fluid like fuser shield, or second type such as a nominal fuser fluid in the RAM assembly of the device depending on what types of jobs will be printed that day, i.e., color or clear toner jobs. The technician must also manually modify system nonvolatile memory (NVM [A, B]) values to match the fuser fluid that has been loaded. A job that requires clear toner needs the first type (fuser shield) fuser fluid to be loaded in the RAM Assembly and the Fuser Ram Counter “A” NVM has to be manually set to an enabled value [1] and Fuser Ram Counter “B” NVM with a disabled value [0]. A job that requires regular colored toner needs the second type of (nominal) fuser fluid loaded in the RAM Assembly and the Fuser Ram Counter “B” NVM has to be manually set to an enabled value [1] and Fuser Ram Counter “A” NVM with a disabled value [0].
A mismatch of fuser fluid with toner like when nominal fuser oil is used for Clear printing, it leaves a messy clear toner residue throughout the paper path, which will translate into a long and expensive service call or the system may suffer from phantom jams due to sensors blocked with clear toner. There is no automatic error checking in the system today to ensure that the proper fuser oil is loaded to match the toner required by the job and the system will print with whatever oil is installed.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art to prevent accidental oil and toner mismatches.